"Thanks for all the congratulations everyone. I'm a very happy lady indeed and all the warm wishes are well appreciated!" the newly engaged actress, 23, wrote in a post on Dec. 7. "We plan to keep our special day very private and we hope everyone can respect that. Thanks for the love, right back atcha!"

Grimes and Beech, 24, began dating earlier this year and have been smitten ever since, insiders tell Us Weekly.

"Josh couldn't see himself being with anyone else so he asked her [to marry him] and she is over the moon about it," a pal told Us of the happy couple. "They fell for each other hard and since they've met, they talk non-stop. If they're not around each other, they're texting, calling and tweeting back and forth all the time."

Grimes is currently shooting the fifth season of "90210;" the CW hit recently aired its one hundredth episode, which featured guest stars Carmen Electra, Taio Cruz and Denise Richards. In addition to modeling for brands like Burberry, Just Cavalli and Levi's 501 Jeans, Beech also designs a line of T-shirts with his friend, Sam Kent.